To force evolution to reload the entire IMAP account is to delete the IMAP folder in the hidden evolution folder in your home folder while evolution is closed.
Alternatively if you have multiple IMAP accounts you can go in to the IMAP folder and delete the folder pertaining to that account.
This will force evolution to reload the entire account.
Hope this helps.
It sounds as though the account has been set-up as a standard IMAP account as a posed to an IMAP+ account. What's the difference I here you say (because if your here you will need to know).
IMAP+ in Evolution is an IMAP IDLE enabled account which means that the client can tell the server to immediately sync all mail meaning that manual or automatic periodic syncing are obsolete.
With this type of account you should see the email as soon as it has arrived with your server.
Due to a bug that is now fixed in 2.32 (the standard version in 10.10 is 2.30.3) you need to check the "Use idle if the server supports it" option in the options tab.